PD-L1 expression is a common clinical predictor of efficacy, but studies have found that PD-L1 expression is spatiotemporally heterogeneous. In other words, PD-L1 expression may differ between surgical and biopsy specimens from NSCLC patients, PD-L1 expression differs between primary and metastatic tumor foci, and PD-L1 expression may change after other treatments (e.g., chemotherapy or radiotherapy); therefore, dynamic monitoring of PD-L1 expression can help physicians understand the immediate disease status of patients and give more effective treatment. However, there is currently no reliable and effective means of effectively monitoring PD-L1 expression dynamically.
TMB (tumor mutational load) is another marker used to predict the efficacy of PD-1/PD-L1 inhibitors. The TMB of blood (bTMB) and the TMB of tissue were not found to be significantly different. There is no clinical evidence at this time, and no relevant guidelines or recommendations, that dynamic monitoring of TMB can increase patient benefit.
Co-reviewed by Dr. Wang Zhen, Deputy Chief Physician, Guangdong Provincial People’s Hospital, Guangdong Lung Cancer Institute Dr. Sun Hao